Planar Hall elements and vertical Hall elements are known types of magnetic field sensing elements that can be used in magnetic field sensors. A planar Hall element tends to be responsive to (i.e., have a major response axis aligned with) magnetic fields perpendicular to a surface of a substrate on which the planar Hall element is formed. A vertical Hall element tends to be responsive to (i.e., have a major response axis aligned with) magnetic fields parallel to a surface of a substrate on which the vertical Hall element is formed.
Other types of magnetic field sensing elements are known. For example, a so-called “circular vertical Hall” (CVH) sensing element, which includes a plurality of vertical magnetic field sensing elements, is known and described in PCT Patent Application No. PCT/EP2008/056517, entitled “Magnetic Field Sensor for Measuring Direction of a Magnetic Field in a Plane,” filed May 28, 2008, and published in the English language as PCT Publication No. WO 2008/145662, which application and publication thereof are incorporated by reference herein in their entirety. The CVH sensing element is a circular arrangement of vertical Hall elements arranged over a common circular implant region in a substrate. The CVH sensing element can be used to sense a direction (and optionally a strength) of a magnetic field in a plane of the substrate. A CVH sensing elements tends to be responsive to (i.e., have a major response axis aligned with) magnetic fields parallel to a surface of the substrate on which the CVH sensing element is formed
Various parameters characterize the performance of magnetic field sensing elements. These parameters include sensitivity, which is a change in an output signal of a magnetic field sensing element in response to a change of magnetic field experienced by the magnetic sensing element, and linearity, which is a degree to which the output signal of the magnetic field sensing element varies in direct proportion to the magnetic field. These parameters also include an offset, which is characterized by an output signal from the magnetic field sensing element not representative of a zero magnetic field when the magnetic field sensing element experiences a zero magnetic field.
Another parameter that can characterize the performance of a CVH sensing element is the speed with which output signals from vertical Hall elements within the CVH sensing element can be sampled, and thus, the speed with which a direction of a magnetic field can be identified. Yet another parameter that can characterize the performance of a CVH sensing element is the resolution (e.g., angular step size) of the direction of the magnetic field that can be reported by the CVH sensing element.
As described above, the CVH sensing element is operable, with associated circuits, to provide an output signal representative of an angle of a direction of a magnetic field. Therefore, as described below, if a magnet is disposed upon or otherwise coupled to a so-called “target object,” for example, a camshaft in an engine, the CVH sensing element can be used to provide an output signal representative of an angle of rotation, and/or a rotation speed, and/or a rotation direction, of the target object.
Some conventional magnetic field sensor arrangements position a magnetic field sensor and associated magnetic field sensing element along an axis of rotation of a ring magnet configured to rotate, the ring magnet coupled to a target object. In these arrangements, the magnetic field sensor is disposed such that the major response axis of the magnetic field sensing element within the magnetic field sensor is perpendicular to the axis of rotation of the ring magnet and parallel to a major surface of the ring magnet.
Other conventional magnetic field sensor arrangements position a magnetic field sensor and associated magnetic field sensing element proximate to a line magnet configured to move linearly, the line magnet coupled to a target object.
However, due to mechanical constraints, the conventional orientations of a magnetic field sensor relative to a magnet may not be achievable in all installations of the magnetic field sensor. Furthermore, the conventional orientations may not achieve a closest distance between the magnetic field sensing element and the magnet, which is desirable for high sensitivity. Therefore it is desirable to provide a magnetic field sensor arrangement for which the magnetic field sensor is positioned such that a magnetic field sensing element therein has an axis of sensitivity not parallel to a surface of the associated magnet.